SEOUL (Reuters) - South Korean officials will make a rare visit to North Korea on Thursday to check Pyongyang's progress in keeping to a disarmament deal, a trip which comes weeks after the North clamped down on its border.

This will be the first South Korean government delegation to visit Pyongyang since President Lee Myung-bak took office in February 2008 and is one of a handful of nuclear teams from the South ever to visit the North.

The foreign ministry said on Tuesday the team will inspect nuclear fuel rods at the North's ageing reactor as part of disablement steps in a stalled disarmament-for-aid deal Pyongyang signed with five regional powers.

The visit comes as North Korea appeared to have extended an olive branch to U.S. President-elect Barack Obama by saying in a New Year's message it is willing to work with countries that are friendly towards it.

South Korean media this week said the North asked to send a top nuclear envoy to Obama's inauguration.

"Our team of inspectors aim to take part in the decision on the handling of unused fuel rods possessed by North Korea and will focus on technical and economic aspects in their work," the ministry said in a statement.

Relations between North and South Korea have been frosty, with the Pyongyang cutting almost all ties with Seoul in anger at the policies of President Lee, who ended what had once been a free flow of unconditional aid to his prickly neighbour and instead tied handouts to progress Pyongyang makes in disarmament.

The communist North and capitalist South are still technically at war, never having signed a formal peace treaty to end hostilities in 1953.

The South Korean team led by Foreign Ministry official Hwang Joon-kook will fly into North Korea from Beijing and is expected to visit the communist state's main nuclear complex in Yongbyon about 100 km (60 miles) north of the capital, Pyongyang.

The United States last month called for a halt in heavy fuel oil aid to punish the North for failing to agree to a system to verify the claims it made about its nuclear arms programme, considered one of the region's greatest security threats.

Analysts said the energy-starved North, whose economy is smaller now than it was 20 years ago, could see a downward slide in production if it lost out on the fuel aid promised to it as a part of the nuclear deal it reached with China, Japan, Russia, South Korea and the United States.

South Korea has been pushing for talks with the North after the sputtering nuclear disarmament process hit another snag late last year after Pyongyang refused to accept a proposal to allow inspectors to take nuclear samples out of the country.

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